Investigation of the $D_{s1}$ structure via $B_c$ to $D_{s1} l^+l^-/\nu\bar\nu$ transitions in QCD

TL;DR

This paper analyzes the structure of $D_{s1}$ mesons through semileptonic $B_c$ decays using QCD sum rules, considering different internal configurations and calculating form factors, decay rates, and branching ratios.

Contribution

It introduces a detailed QCD sum rule analysis of $D_{s1}$ meson structure via rare $B_c$ decay transitions, including mixing effects and gluon condensate contributions.

Findings

Form factors calculated for different $D_{s1}$ configurations.

Decay rates and branching ratios estimated.

Results can inform future experimental studies.

Abstract

We investigate the structure of the $D_{s1}(2460,2536) (J^P=1^+)$ mesons via analyzing the semileptonic $B_{c}\to D_{s1}l^+l^-$, $l=\tau, \mu, e$ and $B_{c}\to D_{s1}\nu\bar{\nu}$ transitions in the framework of the three--point QCD sum rules. We consider the $D_{s1}$ meson in two ways, the pure $|c\bar{s}>$ state and then as a mixture of two $|^3P_1>$ and $|^1P_1>$ states. Such type rare transitions take place at loop level by electroweak penguin and weak box diagrams in the standard model via the flavor changing neutral current transition of $b \to s$. The relevant form factors are calculated taking into account the gluon condensate contributions. These form factors are numerically obtained for $|c\bar s>$ case and plotted in terms of the unknown mixing angle $\theta_s$, when the $D_{s1}$ meson are considered as mixture of two $|^3P_1>$ and $|^1P_1>$ states. The obtained results for the form factors are used to evaluate the decay rates and branching ratios. Any future experimental measurement on these form factors as well as decay rates and branching fractions and their comparison with the obtained results in the present work can give considerable information about the structure of this meson and the mixing angle $\theta_s$.